1. Field of the Invention:
This invention relates to a splicer, splicing method and splice structure for splicing optical fibers.
2. Background Art:
Optical fibers have conventionally been spliced with a mechanical splicer.
A mechanical splicer has a general structure consisting of a base formed with a V-shaped groove (V-groove), a retaining member (flat plate) overlaid on the grooved surface of the base, and a spring for holding the base and retaining member in pressure contact.
The method typically used to splice optical fibers with the mechanical splicer involves first removing the protective coverings from the terminal portions of the optical fibers to be spliced, disposing wedges or the like to form a space between the base and the flat plate into which the exposed optical fibers can be inserted, inserting one fiber into the V-groove at one end of the base, inserting the other fiber into the V-groove at the other end of the base, bringing the two fibers into abutment, removing the wedges, and fixing the fibers by using the retaining member to apply a force orthogonal to the fibers.
Once the force of the plate spring has been applied, a force exerted in the direction of fiber abutment has no effect. Therefore, in order to prevent a gap from forming at the abutting faces of the fibers, matching oil is usually supplied to the abutment region.
Although a device for permanently splicing optical fibers, the mechanical splicer is also sometimes used for temporarily splicing fibers.
However, use of a mechanical splicer for temporary splicing is uneconomical and wasteful of material resources because the splicer is discarded after fulfilling its purpose.
A fiber splicer of nearly the same structure as the mechanical splicer but capable of repeated fiber splicing is also available.
However, this reusable splicer needs to be cleaned of oil and supplied with fresh oil every time it is used.
Moreover, when a multi-filament optical fiber bundle is spliced, differences are likely to occur in the cut length of the individual fibers. With either the mechanical splicer or the reusable fiber splicer, these differences have to be absorbed by use of matching oil. The splice efficiency is therefore likely to be unstable.
An object of the present invention is therefore to provide a splicer, splicing method and splice structure for splicing optical fibers usable with both mono-filament optical fibers and multi-filament optical fiber bundles that enable optical fibers to be directly spliced without use of a connector and splicing to be performed simply without use of matching oil.
In its first aspect, the present invention achieves this object by providing an optical fiber splicer including a pair of retaining means for retaining optical fibers to be spliced, and abutment and pressure-contact means for sliding terminal portions of the optical fibers in mutually opposite directions along a groove of V-shaped cross-section, producing substantially equal elastic forces in the terminal portions, bringing the terminal portions into abutment, and bringing the abutted terminal portions into pressure contact.
By xe2x80x9celastic forcexe2x80x9d here is meant force acting in the direction of restoring the optical fiber to its original state when it is flexed under application of a load.
The elastic forces produced in the terminal portions of the optical fibers gradually increase as the terminal portions slide along the groove of V-shaped cross-section (V-groove) in opposite directions and are of substantially equal magnitude.
The terminal portions of the optical fibers slide along the V-groove under identical conditions, i.e., while being imparted with equal elastic forces in the direction of forcing them into the V-groove, approach each other, abut, and are then forced into pressure contact.
The splicer according to this aspect of the invention therefore enables optical fibers to be easily spliced with high precision, i.e., with substantially no offset between the centers of their terminal portions, without use of a connector or matching oil.
The action and effect of the splicer can be enjoyed not only with mono-filament optical fibers but also with multi-filament optical fiber bundles.
The individual optical fibers act as springs (produce elastic force). Because of this, each produces its own independent pressure-contact force in the direction of the optical fiber with which it is to mate and can therefore absorb any difference in cut length that may arise.
The abutment and pressure-contact means can be a drive mechanism for moving a block formed with the groove of V-shaped cross-section or can be a rotating mechanism for rotating the pair of retaining means.
The splicer can therefore splice optical fiber without using a connector.
The abutment and pressure contact means is not limited to a drive or rotating mechanism but can instead be a slide mechanism as explained in the following.
The optical fiber splicer is preferably equipped with a pressure limiting mechanism for limiting pressure applied by the abutment and pressure contact means to a prescribed value.
The pressure limiting mechanism is provided to protect the optical fibers from breakage by stress in excess of the allowable limit.
In its second aspect, the present invention achieves its object by providing an optical fiber splicing method comprising a step of sliding terminal portions of optical fibers to be spliced along a groove of V-shaped cross-section in mutually opposite directions and producing substantially equal elastic forces in the terminal portions, and a step of bringing the terminal portions into abutment and then bringing the abutted terminal portions into pressure contact.
In its third aspect, the present invention achieves its object by providing an optical fiber splice structure comprising terminal portions of optical fibers spliced in a groove of V-shaped cross-section under pressure contact and exertion of substantially equal elastic forces.
The second and third aspects of the invention provide the same effects and advantages as the first.
In the splicer, splicing method and splice structure for splicing optical fibers according to this invention, the operations of sliding the optical fibers, bringing them into abutment, and bringing them into pressure contact are preferably conducted respectively and simultaneously in the manner of a continuous operation.
In the splicing method and splice structure for splicing optical fibers according to this invention, force is preferably applied to the fibers through a means such as the aforesaid pressure limiting mechanism so as to prevent application of more than a prescribed amount of contact pressure at the abutted fiber faces.